nucl-th digest · Feb 27, 2023

Pairing properties of semilocal coordinate&momentum-space regularized chiral interactions

We investigate the pairing properties of state-of-the-art semilocal coordinate-space and semilocal momentum-space regularized chiral interactions. Specifically, we calculate the pairing gaps in

^{3} S D_{1}

channel of symmetric nuclear matter and in

^{1} S_{0}

and

^{3} P F_{2}

channels of pure neutron matter within the BCS approximation using these chiral interactions. We address the regulator and chiral order dependence of the pairing gaps and compare the pairing properties of the chiral interactions with those of the Argonne v18 (Av18) potential. The effects of the tensor force on the pairing gaps in the

^{3} S D_{1}

and

^{3} P F_{2}

channels are illustrated for both the chiral interactions and the Av18 potential. We evaluate the truncation errors of chiral expansions of the pairing gaps with a Bayesian approach. We find that the pairing gaps converge very well at the higher-order chiral expansions in the

^{3} S D_{1}

and

^{1} S_{0}

channels.

Subjects:: Nuclear Theory (nucl-th)
arXiv:: 2302.12463 [pdf]

PRC(2023)·7 citations

[Submitted on 24 Feb 2023]

Bayesian Analysis of $χ$ EFT at Leading Order in a Modified Weinberg Power Counting Approach

Oliver Thim🇸🇪 · Eleanor May🇸🇪 · Andreas Ekström🇸🇪 · Christian Forssén🇸🇪

We present a Bayesian analysis of renormalization-group invariant nucleon-nucleon interactions at leading order in chiral effective field theory ( $χ$ EFT) with momentum cutoffs in the range 400--4000 MeV. We use history matching to identify relevant regions in the parameter space of low-energy constants (LECs) and subsequently infer the posterior probability density of their values using Markov chain Monte Carlo. All posteriors are conditioned on experimental data for neutron-proton scattering observables and we estimate the $χ$ EFT truncation error in an uncorrelated limit. We do not detect any significant cutoff dependence in the posterior predictive distributions for two-nucleon observables. For all cutoff values we find a multimodal LEC posterior with an insignificant mode harboring a bound $^{1} S_{0}$ state. The $^{3} P_{0}$ and $^{3} P_{2}$ phase shifts emerging from the Bayesian analysis are less constrained and typically more repulsive compared to the results of a phase shift optimization. We expect that our inference will impact predictions for nuclei. This work demonstrates how to perform inference in the presence of limit-cycle-like behavior and spurious bound states, and lays the foundation for a Bayesian analysis of renormalization-group invariant $χ$ EFT interactions beyond leading order.

Comments:: 20 pages, 16 figures
Subjects:: Nuclear Theory (nucl-th)
arXiv:: 2302.12624 [pdf]

PRC(2023)·19 citations

Monday·February 27, 2023

Pairing properties of semilocal coordinate&momentum-space regularized chiral interactions

Bayesian Analysis of $χ$ EFT at Leading Order in a Modified Weinberg Power Counting Approach

Affiliations

Pairing properties of semilocal coordinate&momentum-space regularized chiral interactions

Bayesian Analysis of χEFT at Leading Order in a Modified Weinberg Power Counting Approach

Affiliations

Bayesian Analysis of $χ$ EFT at Leading Order in a Modified Weinberg Power Counting Approach